Paper chemical agent detectors for certain chemical warfare purposes were developed some 20 years ago and have been in widespread use by the military of many nations. In their most sophisticated form these detectors consist of a paper base in which three dyes have been incorporated, each dye being sensitive to a particular family of liquid chemical warfare agent droplets. These droplets react with the specific dyes to produce colour changes on the paper. According to the colour change produced, the type of chemical warfare agent can be identified.
Other forms of paper chemical agent detectors contain only one dye. In these cases not as much information on the type of chemical warfare agent can be obtained from the reaction with the paper detector.
A paper chemical agent detector strip is attached to the clothing or equipment of service personnel so that these personnel can immediately determine whether they or their equipment have been exposed to liquid agent contamination. Also, the paper can be used to determine if an unknown liquid on clothing, equipment, or terrain is a chemical warfare agent.
The preferred method of manufacturing these detectors is to include the dyes in the papermaking slurry so that they are integral with the paper.
As currently utilized the detectors incorporate three dyes, one each for the detection of H-type agents (mustard), G-type nerve agents and V-type nerve agents.
It has come to light that two of the three dyes heretofore incorporated in the detectors are mutagenic. That being the case, it will be very difficult or, more likely, no longer possible to utilize these two dyes. It is therefore required that new dyes be sought which meet the various criteria which are required to make the detectors.
These criteria include insolubility of the dyes in water during the papermaking process and solubility in the appropriate chemical warfare agent. The dyes must be solids with a minimum melting point which will keep them solid during a paper drying process and must give the correct strong colour on reaction with chemical warfare agent droplets. There are various other requirements including compatibility in terms of colour produced with other dyes in the detector.
The present invention provides paper chemical agent detectors incorporating dyes which meet the criteria set out above and which dyes are non-mutagenic.